How can outer space be cold?

[burt-oh-my!]

As I was tossing and turning in bed this morning, the thought jumped into my head from nowhere - how can it be cold (or any temperature for that matter) in outer space, when it is supposedly a complete vacuum? I mean, there would be no air to carry the temperature. If you were able to stretch out your arm in outerspace, why would it feel cold, since it wouldn't be actually 'touching' anything?

 

[diehard]

Ah, what a sleepless night...

That's a good question though.

If you stretch your arm in outer space, where will the heat from his arm be transferred to, considering outer space is empty (vacuum).

Is space really empty though? ie. there will always be some hydrogen atoms hanging around.

 

[whollycheeses]

From wikipedia...

Outer space has very low density and pressure, and is the closest physical approximation of a perfect vacuum. It has effectively no friction, allowing stars, planets and moons to move freely along ideal gravitational trajectories. But no vacuum is truly perfect, not even in interstellar space, where there are still a few hydrogen atoms per cubic centimetre.

 

[Ceiling Cat]

Cold is the absence of heat.

 

[Rigel7]

Accroding to principle's of Ideal Gas Law derived from such phycists as Boyle, Avogadro, Graham etc simple stated
p*V = n*R*T where P is the pressure, v is volume of gas present, n is number of particles of gas in moles, R is the ideal gas constant (2.016 for Hydrogen) and T is the Temperature (in degrees Kelvin). There would be very low pressure and very low volume of gas in outer spance.

 

[Zombie]

Yep. I thought that was common knowledge.

 

[stinkynuts]

http://answers.yahoo.com/question/index?qid=20100227193724AAP9Q3W


Best Answer - Chosen by Asker

In a vacuum, heat can only be transferred 1 way, directly, as electromagnetic radiation. That is, it gets from the sun to us as a form of light- in the infra red spectrum actually.

In an atmosphere, there is another way for heat to get around: hot objects heat up the air around them, the heated air transfers heat outwards and heats up anything else in the area.

But that atmospheric effect is unknown in space. If you have an object in space that is exposed to direct sunlight, it will get really, really hot. Both because it is being bombarded with sunlight, and also because there is no air around it to carry heat away.

But an object in shade, even if its only a few feet away, can get extremely cold: Because it's being hit with NO radiation, which in space is the only source of heat, and there is no air to carry heat to it the other way.

So it's really not accurate to say that "space is cold." Space is just.. space... it has no temperature. Whether an object in space is very cold, or very hot, simply depends on whether the sun is shining on it.

 

[skidoo64]

At the end of the day..
Someone needs to get laid.

Outer space may be cold, but a lady's mouth certainly isn't

 

[Brill]

If it's a vacuum, who changes the bags?

 

[Zombie]

Ugggg... thanks for that one dad.

 

[Cassini]

A person's skin has a delicate osmotic balance that keeps the water inside your body. The nearly limitless vacuum of space would violently disrupt the osmotic balance. The water would literally evaporate (boil) right out of you. Many key membranes would be unable to retain fluid.

It would be like being flash-frozen on earth, then vacuum packed. It would feel incredibly cold.

 

[fuji]

All objects radiate heat, including you and your arm if you were to stick it into space. In the atmosphere heat radiation is not usually as significant as the heat you exchange via conduction with the air around you, but in space obviously there is no exchange of heat via conduction, so it's all about radiation.

Assuming you are in a shadow in space you will radiate heat until your temperature hits absolute zero. This is why space is considered to be "cold" - although space itself is not cold, any matter there will, via radiation, eventually drop to a temperature of absolute zero, unless something else is heats it up.

If you are in space and you're in the sunlight, you will be absorbing heat via radiation and you will become very hot--but that's the outside energy source, the sun, heating you up, not space.

 

[basketcase]

And heat is the absence of cold.

Depends on where you started!
...

Absolutely not. Heat is a measure of the kinetic energy of the particles that make up a substance. The faster the particles move, the more heat. That energy is transferred when the collisions between particles transferring some of that kinetic energy (or by EM/black body radiation being emitted by the object being absorbed by other objects).


Absolute Zero (cold if you prefer) is the temperature where all molecular motion stops (ie. zero kinetic energy). It is only theoretically possible in experiments because the surrounding apparatus and measurement devices will transfer some small amount of heat to the particles being measured. Experiments have been able to reach within a billionth of a degree of absolute zero.

p.s. It is no coincidence that the planned experiments to get closer are to be set in outer space.

 

[Yoga Face]

Assuming you are in a shadow in space you will radiate heat until your temperature hits absolute zero.

No place to radiate your heat into so you should remain at the same temperatue ? unless the sun warms you up ? So eventually you will boil as the radiation of millions of suns reaches you ?

Who said it is cold in space ??

 

[shakenbake]

http://answers.yahoo.com/question/index?qid=20100227193724AAP9Q3W


Best Answer - Chosen by Asker

In a vacuum, heat can only be transferred 1 way, directly, as electromagnetic radiation. That is, it gets from the sun to us as a form of light- in the infra red spectrum actually.

In an atmosphere, there is another way for heat to get around: hot objects heat up the air around them, the heated air transfers heat outwards and heats up anything else in the area.

But that atmospheric effect is unknown in space. If you have an object in space that is exposed to direct sunlight, it will get really, really hot. Both because it is being bombarded with sunlight, and also because there is no air around it to carry heat away.

But an object in shade, even if its only a few feet away, can get extremely cold: Because it's being hit with NO radiation, which in space is the only source of heat, and there is no air to carry heat to it the other way.

So it's really not accurate to say that "space is cold." Space is just.. space... it has no temperature. Whether an object in space is very cold, or very hot, simply depends on whether the sun is shining on it.

Radiative heat transfer
Convective heat transfer
Conductive heat transfer

The only siginificant one in outerspace is radiative heat transfer that depends on differences in transmitter to receiver T to the fourth power temperature differences.

Thermodynamically, temperature is a measure of the internal energy of a substance/object/medium and molecular motion. If there is no material, there can be no thermal content, and zero temperature. As there is not a perfect vacuum, the temperture is very low. Note, however, that the laws of Thermodynamics tell us that we can never achieve absolute zero, where there is no molecular motion, whatsoever.

 

[GPIDEAL]

As I was tossing and turning in bed this morning, the thought jumped into my head from nowhere - how can it be cold (or any temperature for that matter) in outer space, when it is supposedly a complete vacuum? I mean, there would be no air to carry the temperature. If you were able to stretch out your arm in outerspace, why would it feel cold, since it wouldn't be actually 'touching' anything?

Who said that a vacuum be devoid of any kind of temperature? On a cold sunny day, it feels warmer because of the solar radiation. On a cold cloudy day, it feels colder. In each example you have air.

In the vastness of space, between sources of heat and radiation, you have cold. It's as simple as that. And it's more than just cold. It's like minus 200 Kelvin or whatever it is.

I think it might have something to do with the absence of air or matter. If there's nothing to absorb solar radiation, then it's cold. (What Shakenbake said, lol).

 

[KBear]

A thermos uses a vacuum as an insulator to surround liquids and help them hold their heat. If a person was in a glass bottle so as not to lose air, and placed in deep space, would they also stay warm for many days?

 

[Mervyn]

A thermos uses a vacuum as an insulator to surround liquids and help them hold their heat. If a person was in a glass bottle so as not to lose air, and placed in deep space, would they also stay warm for many days?

Assuming the glass survives the rigors of space

No, glass, even though it's an insulator, will still absorb heat and try to create an equilibrium with the termperature outside of the glass bottle. So if the temperate inside the bottle was 20 degrees C , it would try to seek an equilibrim with the outside temperate, which is over 200 degress C below O.

I don't know how long it will take, but it will not stay warm forever without a heat source withing the bottle to maintain temperature.

 

[GirlFriends Toronto]

Accroding to principle's of Ideal Gas Law derived from such phycists as Boyle, Avogadro, Graham etc simple stated
p*V = n*R*T where P is the pressure, v is volume of gas present, n is number of particles of gas in moles, R is the ideal gas constant (2.016 for Hydrogen) and T is the Temperature (in degrees Kelvin). There would be very low pressure and very low volume of gas in outer spance.

ohh that's hot!

 

[shakenbake]

ohh that's hot!

Then, you will enjoy riding across the Wheatstone bridge on my Megacycle before I short your shunt with my high voltage probe. You wil be yelling "Mho, Mho, Mho!"